Mattstang a Stuck case usually is the result of , yes a cold steel laquered case going into a hot steel chamber. After many rnds that laquer builds up and will grab that case like you cant believe. Especially if you shoot like 20 rnds out of a 30 rnd mag and stop leaving one in , put safety on, look thru spotting scope to check target and such. If that chamber cools you just glued yourself stuck and when you fire that rnd it will rip the bottom right off that case. Not all the time but it does happen. You can stop and leave a brass case in forever and it will never stick to steel.
A stuck case remover tool is an excellent tool to have no matter the gun or caliber.
Only like 10-20 bucks for a good one.
AKs and SKS' traditionally have much looser chambers and some even have flutes in them to help disperse what is anticipated to be laquered ammo going thru.
Our styles of guns Mini 14s and ARs have a tighter chamber usually for better accuracy.